iridoids and boric-acid

Mounting evidences have recognized that dual cross-link and double-network gels can promisingly recapitulate the complex living tissue architecture and overcome mechanical limitations of conventional scaffolds used hitherto in regenerative medicine. Here, dual cross-link gels formed of a bioactive lactose-modified chitosan reticulated via both temporary (boric acid-based) and permanent (genipin-based) cross-linkers are reported. While boric acid rapidly binds to lactitol flanking diols increasing the overall viscosity, a slow temperature-driven genipin binding process takes place allowing for network strengthening. Combination of frequency and stress sweep experiments in the linear stress-strain region shows that ultimate gel strength, toughness, and viscoelasticity depend on polymer-to-genipin molar ratio. Notably, herewith it is demonstrated that linear stretching correlates with strain energy dissipation through boric acid binding/unbinding dynamics. Strain-hardening effect in the nonlinear regime, along with good biocompatibility in vitro, points at an interesting role of present system as biological extracellular matrix substitute.

Topics: Biocompatible Materials; Boric Acids; Chitosan; Gels; Humans; Iridoids; Lactose; Regenerative Medicine; Stress, Mechanical; Viscosity

A micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of four bioactive constituents (morroniside, loganin, paeoniflorin and paeonal) in the Chinese patent medicine Liuwei Dihuang Pills is established. A carrier composed of 0.2M boric acid, 0.02 M sodium dodecyl sulfate (SDS) and 5% acetonitrile (pH was adjusted to 10.5 with 0.1 M NaOH) is found to be the most suitable electrolyte for this separation. The four constituents in Liuwei Dihuang Pills can be easily determined within 16 min. Optimization of separation is realized with the univariate approach by studying the effects of four factors relevant to run buffer on migration times.

Topics: Acetonitriles; Benzoates; Boric Acids; Bridged-Ring Compounds; Buffers; Chloramphenicol; Chromatography, Micellar Electrokinetic Capillary; Drug Carriers; Drugs, Chinese Herbal; Glucosides; Glycosides; Humans; Hydrogen-Ion Concentration; Iridoids; Molecular Structure; Monoterpenes; Reference Standards; Reproducibility of Results; Sodium Dodecyl Sulfate; Time Factors